The present invention relates to elastomeric articles such as gloves with an antimicrobial coating, which allows the articles to maintain a high efficacy of antimicrobial activity. Gloves according to the invention are particularly, but not exclusively, useful for medical applications, for example as both exam and surgical gloves. Medical gloves according to the invention exhibit good “time-kill” activity against a broad spectrum of microorganisms and maintain their antimicrobial activity after being stored and transported under warm and humid environments. The invention may alternatively have applications in other skin protection environments including, but not limited to, food-contact gloves, dental gloves, industrial gloves, laboratory gloves, and other medical devices such as catheters, protective covers and tubes.
Gloves have become an everyday part of clinical practice for healthcare workers and function as an element of personal protective equipment, which safeguard both the glove wearer and the patient from infection. Hospital acquired infection can be further reduced by compliance With hand washing and glove isolation procedures. Even though the glove protects the individual wearing the glove, cross-contamination may still occur, i.e., patient-to-patient, surface-to-surface and surface-to-patient. For example, the surface of a glove can become contaminated after being in contact with bodily fluids that contain infectious microbes. These microbes can grow on the surface of the glove and eventually be transferred to another person or surface.
To address the problem of infection and cross-contamination, efforts are underway to develop antimicrobial gloves. An antimicrobial glove requires that a glove surface have “quick-kill” properties, i.e., microorganisms are killed on contact with the glove surface. Treating a glove surface with non-volatile water-soluble antimicrobial agents is one approach to meeting the “quick-kill requirement” and cationic bis-biguanide and quaternary ammonium salt are two types of effective antiseptic/disinfectant agents. Chlorhexidine digluconate (CHG) and benzalkonium chloride (BKC) are acceptable examples of these types of agents, respectively.
However, an unresolved problem for developing effective antimicrobial gloves is the difficulty of maintaining the antimicrobial efficacy following production. Glove products are made of either thermosets such as natural rubber and synthetic rubber, including nitrile rubber or thermoplastics such as styrene-type block copolymers and polyurethanes. These elastomeric products possess excellent mechanical properties such as deformation resistance but they can be also be sensitive to liquid or moisture permeation, swelling or absorption. The degree of glove-liquid interaction depends upon the type of elastomers and the chemical nature of the penetrants. Antimicrobial agents coated on the glove surface are not chemically bound to the surface and tend to migrate into the glove substrate when moisture is absorbed by the glove surface. This type of moisture absorption takes place during glove storage. The moisture provides a vehicle for the diffusion of the antimicrobial agent into the body of the glove. As a result, when gloves are finally ready for use in a hospital setting, the availability of antimicrobial agents on the glove surface can be significantly reduced and antimicrobial efficacy can be compromised by virtue of migration of the antimicrobial agent away from the surface and into the glove itself. The loss of antimicrobial agent from the glove surface during storage is accentuated in warm and/or humid environments.
Previous attempts to preserve antimicrobial efficacy tried to localize and fix the antimicrobial agent on the surface of the glove and include the use of starch powders on the surface of the treated gloves. For example, U.S. Pat. No. 5,089,205 requires the presence of starch powder as a carrier for an antimicrobial agent. In addition, U.S. Pat. No. 5,492,692 describes a high-energy co-precipitate powder of polyvinylpyrrolidone/iodine and an anti-HIV agent such as Nonoxynol-9 as a powder coating on elastomeric articles. However, the disclosures discussed above do not provide essentially powder-free gloves and other elastomeric articles with sustainable, broad-spectrum antimicrobial activity. U.S. Pat. Publication No. 2005/0186258 describes a coating on elastomeric articles consisting of CHG, BKC and a moisture resistant package, which maintained antimicrobial activity after aging at 40° C./70% relative humidity. This patent does not provide the elastomeric articles with sustainable antimicrobial activities.
The phrase “sustainable, broad-spectrum antimicrobial activity” as used herein refers to two properties. In one embodiment, the phrase refers to an elastomeric article such as a glove, which retains its antimicrobial activity for a long shelf life as defined in ASTM D 7160-05. In another embodiment, the phrase refers to an elastomeric article such as a glove which maintains its broad-spectrum antimicrobial activity after its packaging is opened, which normally spans an extended period of time i.e., no less than about one week under ambient conditions. Broad-spectrum refers without limitation to gram-positive bacteria such as Staphylococcus aureus and Enterococcus faecalis, and Gram negative bacteria such as Escherichia coli and Pseudomonas aerignosa, and clinical isolates such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE). The above bacteria can be found in a hospital environment.
Therefore, there is a need for powder-free medical gloves and other elastomeric articles, which exhibit effective and sustainable antimicrobial activity against a broad-spectrum of microorganisms.
One objective of the invention is to develop elastomeric articles such as medical gloves with a surface treatment having sustainable antimicrobial properties, i.e., maintain quick-kill activity against microbes, even after an extended period of time, i.e., no less than about one week under ambient conditions without sacrificing other properties. The sustainability can be determined using accelerated age testing, where gloves are subjected to elevated temperatures for a given length of time (7 days at 70° C., ASTM D 6319-00aε3, Test Method D 573). Another objective of the invention is to develop a novel surface coating formulation which can protect an antimicrobial agent from loss of activity due to the presence of moisture, which enhances migration of the antimicrobial agent into the body of the glove over time. An additional objective of the invention is to develop a processing method, glove coating treatment and glove packaging for manufacturing sustainable antimicrobial elastomeric articles such as medical gloves.